During operation, room air is drawn into the inlet grille at the work access opening and through a supply HEPA filter. Approximately 70% of the HEPA-filtered air is circulated through the cabinet, while 30% passes through an exhaust HEPA filter and is discharged. These biohazard cabinets are designed to discharge HEPA-filtered exhaust air directly into the laboratory, or into an exhaust system through the optional Canopy Connection. When canopy-ducted, these biological safety cabinets may be used for applications involving minute quantities of volatile toxic chemicals and tracer amounts of radionuclides as an adjunct to microbiological research.